If unsuccessful, open the System
Control Panel and select Get
more features with a new edition of Windows link. Reinstallation
of Windows is not required (only a change of the Windows
product key is required). If you decide to upgrade to a new version of
Windows instead (e.g. Windows 7 to Windows 8) and you have the system
drive encrypted by TrueCrypt, it must be decrypted first (the upgrade
requires reinstallation).